Why should Jaguar have such a problem with something as simple as a coolant temperature gauge! More than sixty years and they still haven't got it right.

Back in the days of MkII they used to read high with the slightest temperature increase and this concerned many owners. Jaguar's reaction with the introduction of XJ6 in 1968 was to have a temperature needle that oscillated gently like a pendulum. Quite mesmerising but totally useless.

With XK8 in 1996, the temperature gauge rose to approximately one quarter of the way across the scale and stayed solidly there unless the engine dumped all its coolant and was on the point of welding itself into a solid mass. This device soon became known as an 'idiot gauge' because an owner would have to be one to rely on it. I suggested an alternative but it was not adopted:






Advance to the XK in 2006 and the coolant gauge ........... disappeared entirely. There is only a red warning light illuminating shortly before the engine self-destructs due to chronic overheating.

2016 and the F-PACE saw the return of the coolant gauge (item 4) neatly paired in the centre of the Instrument Pack with the clock (item 1) and the fuel gauge (item 5).





Clearly JLR were determined to crack this issue and brought in an outside coolant gauge expert who worked in complete secrecy and wasn't allowed to talk to anyone in the company. What other explanation could there be for a fuel gauge on the right which has a bar to indicate the level and a coolant gauge on the left which has a tiny left triangle to indicate the temperature. Perhaps they should have made a more rigorous check of the coolant gauge expert's CV.

The tiny triangle also remains obstinately in the centre of the scale so I suspect we are seeing the return of the 'idiot gauge'

Graham

 

On VAG cars there are 2 sensors built into 1 widget - 1 for the dash which remains fairly constant (8 bit), and the 2nd feeding info to the ECU for the actual temperature (64 bit). (bit reference for visual representation only not one ounce of evidence to support otherwise lol)
I think I have noticed the difference in the fuel vs temp gauge but never acknowledged it - gonna bug me from here on in lol
do you have a scanner that returns live info to see what is actually going on?
in ye old days smith gauges were governed buy a not so accurate regulator - in a mini once the fuel gauge read 1/4 you needed to get yourself to a garage as it was a gamble from there on lol

 

On both my 2001 XKR & 2010 XF, the temperature gauge always read "NORMAL". Jaguar engineers decided that the gauges should always read normal on a $120K car. I plugged an external coolant temperature gauge into the OBD port on both cars. It gave me an accurate reading, even when driving up a mountain road in mid-summer.